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Proceedings - 2nd International Symposium on 3D Data Processing, Visualization, and Transmission. 3DPVT 2004

作者： Bogomjakov, Alexander Gotsman, Craig Ctr. Graphics and Geometric Comp. Computer Science Dept. Technion - Israel Inst. of Technol. Haifa 32000 Israel

ISBN: (纸本)0769522238

Height fields and depth maps which we collectively refer to as z-fields, usually carry a lot of redundant information and are often used in real-time applications. This is the reason why efficient methods for their simplification are necessary. On the other hand, the comp.tation power and programmability of commodity graphics hardware has significantly grown. We present an adaptation of an existing real-time z-field simplification method for execution in graphics hardware. The main parts of the algorithm are implemented as fragment programs which run on the GPU. The resulting polygonal models are identical to the ones obtained by the original method. The main benefit is that the comp.tation load is imposed on the GPU, freeing-up the CPU for other tasks. Additionally, the new method exhibits a performance improvement when comp.red to a pure CPU implementation. © 2004 IEEE.

关键词： Maps

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The VesselGlyph: Focus & context visualization in CT-angiography

The VesselGlyph: Focus & context visualization in CT-angiogr...

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IEEE Visualization 2004 - Proceedings, VIS 2004

作者： Straka, Matúš Köchl, Arnold Červeňanský, Michal Šrámek, Miloš Fleischmann, Dominik La Cruz, Alexandra Gröller, Eduard Commn. for Scientific Visualization Austrian Academy of Sciences Medical University of Vienna Austria Comenius University Bratislava Slovakia Stanford University Medical Center United States Inst. Comp. Graphics and Algorithms Vienna University of Technology Austria

ISBN: (纸本)0780387880

Accurate and reliable visualization of blood vessels is still a challenging problem, notably in the presence of morphologic changes resulting from atherosclerotic diseases. In this paper we take advantage of partially segmented data with approximately identified vessel centerlines to comp.ehensively visualize the diseased peripheral arterial tree. We introduce the VesselGlyph as an abstract notation for novel focus & context visualization techniques of tubular structures such as contrast-medium enhanced arteries in CT-Angiography (CTA). The proposed techniques combine direct volume rendering (DVR) and curved planar reformation (CPR) within a single image. The VesselGlyph consists of several regions where different rendering methods are used. The region type, the used visualization method and the region parameters depend on the distance from the vessel centerline and on viewing parameters as well. By selecting proper rendering techniques for different regions, vessels are depicted in a naturally looking and undistorted anatomic context. This may facilitate the diagnosis and treatment planning of patients with peripheral arterial occlusive disease. In this paper we furthermore present a way how to implement the proposed techniques in software and by means of modem 3D graphics accelerators. ©2004 IEEE.

关键词： Angiography

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The comp.exity of Jensen's algorithm for counting polyominoes

The complexity of Jensen's algorithm for counting polyominoe...

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Proceedings of the Sixth Workshop on Algorithm Engineering and Experiments and the First Workshop on Analytic algorithms and Combinatorics

作者： Barequet, Gill Moffie, Micha Ctr. Graphics and Geometric Comp. Dept. of Computer Science Technion - Israel Inst. of Technol. Haifa 32000 Israel

ISBN: (纸本)0898715644

Recently I. Jensen published a novel transfer-matrix algorithm for comp.ting the number of polyominoes in a rectangular lattice. However, his estimation of the comp.tational comp.exity of the algorithm (O((√2) n)) where n is the size of the polyominoes), was based only on empirical evidence. This paper is based primarily on an analysis of the number of some class of strings that plays a significant role in the algorithm. It turns out that this number is closely related to Motzkin's numbers. We provide a rigorous comp.tation that roughly confirms Jensen's estimation. We obtain the bound O(n5/2(√3)n) on the running time of the algorithm, while the actual number of polyominoes is about C4.06n/n, for some constant C > 0.

关键词： comp.tational comp.exity

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Video watermarking based on time-axis template

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Tien Tzu Hsueh Pao/Acta Electronica Sinica 2004年第8期32卷 1236-1238页

作者： Niu, Xia-Mu Schmucker, Martin Busch, Christoph Harbin Inst. of Technol. P.O. Box 339 Harbin 150001 China Framhofer Inst. for Comp. Graphics Fraunhoferstr 5 D-64283 Darmstadt Germany

A video watermarking which resists affine transformations is proposed. A template along the time axis is inserted in each Watermark Minimum Segment (WMS) of the video sequence. Experimental results show that the water... 详细信息

关键词： Digital watermarking

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Semantically controlled LMV techniques for plant design review

Semantically controlled LMV techniques for plant design revi...

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2004 ASME Design Engineering Technical Conferences and comp.ters and Information in Engineering Conference

作者： Posada, Jorge Wundrak, Stefan Stork, Andre Toro, Carlos VICOMTech Research Center Parque Tecn. Miramón Paseo Mikeletegi 57 20009 Donostia-San Sebastián Spain Fraunhofer Inst. for Comp. Graphics Fraunhoferstr. 5 D-64283 Darmstadt Germany

Inspecting large industrial plants in a virtual walkthrough environment has proven to be a valuable tool in Plant Design. Many CG techniques, such as various LOD and culling methods, have been developed to visualize comp.ex models in VR environments. These techniques decide solely based on geometric properties how to optimize the scene. In this paper we introduce the concept of semantically controlled selection of those techniques and show how semantic considerations can enhance the CAD to VR conversion process for large model visualization (LMV) walkthroughs of Plant Design models, improving the performance and adapting the visualization to the users' needs. A taxonomy, together with semantic considerations coming from the relationship between user, model, and resources is the basis to decide which rules should be applied for a specific visualization technique. By extending a LMV walkthrough system we are able to reduce the comp.exity of large industrial plant models by a factor of two. On a common workplace PC the semantic preprocessing takes only 10-20 minutes for models with 106 to 10 polygons. Our approach is orthogonal to commonly known CG techniques and can be combined beneficially with those approaches.

关键词： comp.ter aided design

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Augmented-reality-based liver-surgical planning system

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European Surgery - Acta Chirurgica Austriaca 2004年第5期36卷 270-274页

作者： Werkgartner, G. Lemmerer, M. Hauser, H. Sorantin, E. Beichel, R. Reitinger, B. Bornik, A. Leberl, F. Mischinger, H.J. Division of General Surgery Department of Surgery Medical University of Graz Graz Austria Department of Radiology Medical University of Graz Graz Austria Inst. for Comp. Graphics and Vision Graz University of Technology Graz Austria Division of General Surgery Department of Surgery Medical University of Graz 8036 Graz Auenbruggerplatz 29 Austria

Background: The preoperative planning of liver resections is commonly based on two-dimensional imaging techniques such as sonography, comp.ted tomography (CT), and magnetic resonance imaging. The operability of liver tumors depends on the three-dimensional relation of the parenchyma to be resected to the intrahepatic vascular structures which define the autonomously functioning liver segments. Our aim was to establish a liver surgery planning system (LSPS) for major liver resections by augmented-reality (AR) techniques for the accurate evaluation of operability. Methods: The system provides methods for the processing and preparation of the input CT data, three-dimensional visualization, and resection planning. The output consists of quantitative indices (e.g., volume of liver tumors or segments) and an elaborated plan for the surgical procedure including information like the number of liver segments subject to resection and their spatial arrangement or the volume of the remaining or the removed liver tissue. Basically, the LSPS comp.ises two main comp.nents, a medical image analysis and an AR system. The medical image analysis part is responsible for the segmentation of the liver, the vascular structures, and the tumors and for liver segment approximation. The AR system is utilized for visualization and various kinds of user interaction. Results: Experiments with anonymized CT data sets demonstrated the ability of surgeons to deal with different tasks in resection planning after a brief introduction. This led also to a high acceptance by colleagues who wanted to get information for their surgical strategy as quickly as possible. Conclusions: Quantitative measurements are of major importance for the planning of liver resections, for which precise measurements of distances and volumes are required. On the basis of the patient's CT dataset, the LSPS supports an effective way to find the optimal surgical strategy for each patient. The flexible design of this system allo

关键词： Image processing Liver resection planning Medical imaging Three-dimensional visualization

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Robust occupancy detection from stereo images

Robust occupancy detection from stereo images

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Proceedings - 7th International IEEE Conference on Intelligent Transportation Systems, ITSC 2004

作者： Alefs, Bram Clabian, Markus Bischof, Horst Kropatsch, Walter Khairallah, Farid Adv. Comp. Vision GmbH ACV Vienna Donau-City-Strasse 1 A-1220 Vienna Austria Advanced Computer Vision GmbH ACV Farmington Hills MI 48335 United States Inst. for Comp. Graphics and Vision Graz University of Technology Inffeldgasse 16 2. OG A-8010 Graz Austria Computer Science Department Inst. of Computer Aided Automation Vienna University of Technology Favoritenstrasse 9/1832 A-1040 Vienna Austria TRW Automotive 24175 Research Drive Farmington Hills MI 48335 United States

Vehicle occupants that are out-of-position can be deadly injured by the deployment of the air bag in a crash situation. In recent years many different sensors and systems have been proposed to detect the type of occupant and the position of the occupant's head. This paper presents a method for classification and occupant's head detection based on passive stereo vision. The proposed system uses depth surface analysis and scene statistics together with support vector machines for classification and selection of head candidates. Evaluation of the method shows 99% correct for classification and 98% correct for head detection, using large sets of image data, and image sequences recorded in a driving vehicle.

关键词： Stereo vision

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Improved adaptive interpolation algorithm based on edge for image zooming

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Ruan Jian Xue Bao/Journal of Software 2004年第SUPPL.期15卷 68-73页

作者： Chen, Bei-Jing Chen, Gang Wei, Ping Zhao, Xiao-Yu Inst. of Comp. Graphics Zhejiang Univ. Hangzhou 310027 China Inst. of DSP and Software Technique Ningbo Univ. Ningbo 315211 China

Usually, image zooming is an interpolation of the original image, achieving high quality zooming image as fast as possible. But it is well known that many traditional interpolation methods such as bilinear or bicubic often suffer from blurring edges or introduce zigzag errors. In this paper, a new adaptive image interpolation method based on edge, introducing rectangular interpolation and quincunx interpolation, putting forward the gradient weight function, motivated by the work of Nira Shezaf et al., is presented. The experimental results show that the new method can improve the quality of zoomed image effectively. At last, an evaluation is presented assess the quality of zoomed image.

关键词： Adaptive algorithms

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Evaluation of the interpolation algorithms based on Hausdorff distance

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Ruan Jian Xue Bao/Journal of Software 2004年第SUPPL.期15卷 164-168页

作者： Wei, Xue-Hui Chen, Gang Chen, Bei-Jing Inst. of Comp. Graphics Zhejiang Univ. Hangzhou 310027 China Inst. of DSP and Software Techniques Ningbo Univ. Ningbo 315211 China

The technique of image interpolation is usually required in image zooming. In this paper we make some changes to Hausdorff distance based on the theory of Hausdorff measurement. Then we use the changed Hausdorff distance to evaluate the interpolation algorithms. And also we comp.re it with other evaluation methods and we can find that Hausdorff distance has better results and more identical to the vision impress.

关键词： Image processing

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User control strategies for comp.icated information systems

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Jisuanji Jicheng Zhizao Xitong/comp.ter Integrated Manufacturing Systems, CIMS 2004年第SUPPL.期10卷 105-113页

作者： Sun, Hong-Bo Yan, Bo Huang, Bi-Qing Zheng, Guo-Qin Inst. of Comp. Graphics Sch. of Software Tsinghua Univ. Beijing 100084 China Natl. CIMS Eng. and Res. Ctr. Tsinghua Univ. Beijing 100084 China

comp.icated information systems under network environment commonly faced with problems of end-users rights identification, right properties definition, dynamic rights configuration, and active protection under an open or semi-open environment, whereas traditional users' static rights configuration management and direct authorization couldn't solve these problems. The user control strategies based on authorization objects were proposed, which consisted of three stages: identification authentication, access control and operation monitor. In identification authentication stage, the user's identification authorization under an open and semi-open environment was solved. In access control stage, authorization object was introduced to resolve rights properties definition, dynamic rights assignment, and rights identification of end-users. And the operation monitor stage was mainly focused on active protection.

关键词： Management information systems

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